This article reports the findings of a two-year transdisciplinary research project that explored the implications of climate change for the security and safety of drinking water supplies in three communities in Te Hiku o te Ika in Aotearoa New Zealand. In this region, potable water comes mainly from “roof and tank” systems. The project was designed as integrative Kaupapa Māori research utilising climate science, microbiology and social science to develop community-oriented approaches for dealing with the complex issues at the nexus of climate change.